Ecoeffective production of timber

Abstract

Development in surface mould growth on painted/unpainted wooden claddings and acting climatic factors were investigated over a period of 3 years. Eight wood substrates, including modified, preservative-treated and untreated wood, were tested in combination with three types of paint: (1) water-borne alkyd modified acrylic paint without fungicide; (2) solvent-borne alkyd paint without fungicide; and (3) ICP (internal comparison product). One set of samples was exposed unpainted. The samples were tested according to a modified version of EN 927-3. A logistic regression model was fitted to the data. The degree of mould growth varied with exposure time, coating typology, wood substrate, temperature and relative humidity. Exposure time and coating typology contributed most to the model. After 3 years of outdoor exposure unpainted panels and panels coated with solvent-borne paint without fungicide had more mould growth than panels coated with ICP and water-borne paint without fungicide. Unpainted oil/copper–organic preservative-treated claddings had higher resistance to mould growth than other unpainted wood substrates. Coated untreated pine and coated acetylated pine were more susceptible to mould growth than other coated wooden substrates.     

Moisture conditions in coated wood panels during 24 months natural weathering at five sites in Europe

Abstract

Wood moisture content of coated panels of Scots pine sapwood was recorded during 24 months natural weathering in Vienna by logging electric resistance and temperature near the surface. Eight coating systems with various film thicknesses were used, including three solvent borne alkyd stains, three water borne acrylic stains and two water borne acrylic paints. At five sites in Europe wood moisture content of panels coated with three solvent borne alkyd stains, a brown acrylic stain and a white opaque acrylic paint was recorded weekly by changes in panel mass. Fluctuations in wood moisture content were influenced by the film thickness, water permeability and colour of the coating systems used. Degradation phenomena led to decreasing moisture protection of less durable coating systems over time of exposure. The exposure site clearly affected wood moisture content in the panels.     

Weathering durability of CCB-impregnated wood for clear varnish coatings

Outdoor performances of a polyurethane varnish and an alkyd-based synthetic varnish coated over chromium-copper-boron (CCB)-impregnated Scots pine (Pinus sylvestris L.) and chestnut (Castanea sativa Mill.) [10 (R) × 100 (T) × 150 (L) mm] were investigated. These varnishes were also applied to the wood surface as sole coatings or impregnated into wood as water-repellent (WR) solutions. Outdoor exposure was performed in the Black Sea region of northern Turkey (41°N, 39.43°E) where humid weather predominates throughout the year and accelerates decomposition of coated wood surfaces. The wood panels were exposed at 45° south on their tangential surfaces. After 9 months of exposure to summer, autumn, and the following winter season, the color and glossiness changes of the exposed surface, adhesion of the coating layer to the wood surface, water absorption through the coating layers, mass loss, and the hardness of the board surface were studied. CCB impregnation greatly stabilized the surface color of varnish-coated panels of both wood species. Gradual decreases of adhesion between varnished layers and preimpregnated surfaces were attributed to probable weakening of interactions at the interface of the treated wood and the film layer. A superficial cleaning process of treated wood is suggested to improve glossiness and adhesion. The coated wood surface became harder with time on outdoor exposure until a maximum hardness occurred followed by softening, whereas the uncoated surface softened steadily. Polyurethane varnish yielded a harder surface than synthetic varnish. Mass losses of wood panels after 9 months of exposure were negligible for all treatments compared with the untreated controls, which were totally discolored and eroded on the surface. It is concluded that long-term exterior wood protection has been achieved by a successful combination of an appropriate preservative treatment followed by a compatible surface-coating process.     

Photodegradation at the wood-clearcoat interface

Summary Western red cedar panels, one coated with a soft latex-based acrylic polymer clear coating and the other uncoated, were exposed outdoors under a series of cut-off filters for 50 weeks. FTIR-ATR spectra of the panels showed that the extent of delignification increased with decreasing wavelengths of the solar radiation incident at the wood surface. The results support the proposal that it is the UV component of sunlight that is primarily responsible for the degradation of lignin. The extent of loss of lignin from the surface of the exposed coated panel was significantly less than that for the exposed uncoated panel suggesting that the coating confers some protection from weathering to the underlying timber. Colorimetric measurements also showed that the degree of discoloration of the panels is related to the wavelength of the radiation penetrating the wood surface.This work was supported financially by ICI Dulux Australia and the Australian Research Council. The authors also express their appreciation for helpful discussions with G. J. Wilson of the Commonwealth of Australia Scientific and Industrial Research Organization (C.S.I.R.O.) and I. Leaver of Dulux Australia     

The influence of different soil substrates on the service life of Scots pine sapwood and oak heartwood in ground contact

The durability of wood in ground contact is affected by numerous influences, such as substrate quality, climate and microflora of the soil, which need to be considered for the prediction of service life of wooden components to be used in the ground. In this study the influence of different soil substrates on the service life of Scots pine sapwood (Pinus sylvestris L.) and oak heartwood (Quercus petraea Liebl.) was investigated. Mini-stakes were exposed in six different soils at the test site of the Federal Research Centre for Forestry and Forest Products (BFH) in Hamburg, Germany. The effect of partly embedding the test samples in concrete or polyethylene films was also examined. After 3 years of exposure the decay rates for both wood species differed significantly between the soil substrates. Compost soil and fertilized test field soil induced the highest decay activity, whereas in pure sand the lowest decay rates were observed. Surprisingly, exposure in gravel also led to higher decay ratings than sand. Protective measures by means of concrete embedding and polyethylene films performed well during the first 2 years of exposure, but showed increasing decay rates in the third year. The overall decay rating for all soil types was higher for oak heartwood than for pine sapwood. The meaning of different soils, independent of other site influences, for service life prediction of wood is discussed, and the need for further studies on this topic is highlighted.     

桉树栽培灵芝试验及灵芝营养成分分析

以桉树段木和桉木屑为基质,杂木屑为对照,开展了桉树栽培灵芝对比试验,并对灵芝主要营养成分和重金属含量进行了检测。结果表明:桉树栽培灵芝是可行的,桉树栽培灵芝菌丝生长快(桉木屑灵芝菌丝日长速9.75 mm·d-1、桉树段木灵芝菌丝日长速7.28 mm·d-1);桉木屑混合基质灵芝的单芝鲜重(47.66 g)比对照灵芝(47.11 g)高1.18%,而桉树段木灵芝(45.44 g)比对照的低3.53%;桉木屑基质灵芝多糖(1.64 g·100 g-1)和比对照灵芝多糖(1.44 g·100g-1)高13.89%,桉树段木灵芝多糖与对照的相同,桉木屑基质灵芝三萜化合物(1.88 g·100 g-1)比对照灵芝(1.38 g·100 g-1)高36.23%;桉树灵芝重金属含量均符合绿色食品食用菌的要求。     

The influence of different soil substrates on the service life of Scots pine sapwood and oak heartwood in ground contact

Abstract

The durability of wood in ground contact is affected by numerous influences, such as substrate quality, climate and microflora of the soil, which need to be considered for the prediction of service life of wooden components to be used in the ground. In this study the influence of different soil substrates on the service life of Scots pine sapwood (Pinus sylvestris L.) and oak heartwood (Quercus petraea Liebl.) was investigated. Mini-stakes were exposed in six different soils at the test site of the Federal Research Centre for Forestry and Forest Products (BFH) in Hamburg, Germany. The effect of partly embedding the test samples in concrete or polyethylene films was also examined. After 3 years of exposure the decay rates for both wood species differed significantly between the soil substrates. Compost soil and fertilized test field soil induced the highest decay activity, whereas in pure sand the lowest decay rates were observed. Surprisingly, exposure in gravel also led to higher decay ratings than sand. Protective measures by means of concrete embedding and polyethylene films performed well during the first 2 years of exposure, but showed increasing decay rates in the third year. The overall decay rating for all soil types was higher for oak heartwood than for pine sapwood. The meaning of different soils, independent of other site influences, for service life prediction of wood is discussed, and the need for further studies on this topic is highlighted.     

Microscopic observation of wood-based composites exposed to fungal deterioration

This study was conducted to investigate the susceptibility of various wood composite panels exposed to wood-deteriorating fungi. Five wood-attacking fungi (three mold fungi, one brown rot fungus, one white rot fungus) were inoculated into four types of commercial wood composite panels (plywood, oriented strand board, particleboard, and medium-density fiberboard). One solid wood sample was included as a control. The attacking patterns of the fungi in each panel was observed by scanning electron microscopy. The weight losses due to the exposure were compared. All wood composites were more or less susceptible to all fungi inoculated. The attacking mode of the fungi was highly dependent on the types of wood composite, which had inherently different shapes of voids owing to different shapes and characteristics of the raw furnish materials used. Plywood and medium-density fiberboard showed a large weight loss after an 8-week exposure to decay fungi. Plywood is the most susceptible to white and brown rot fungi. This study indicates that all wood composite panels should undergo careful consideration to prevent fungal deterioration when they are used for exterior and humid interior applications.     

Saproxylic beetle assemblages on low stumps,high stumps and logs: Implications for environmental effects of stump harvesting

The aim of this study was to evaluate how future harvesting of spruce low stumps as a renewable energy source, might influence the saproxylic (wood living) beetle fauna. Species richness, abundance and assemblages of saproxylic beetles were compared on low stumps, high stumps and logs of spruce on 10 clear-cuts in northern Sweden. The sampling was conducted with emergence traps and a total of 929 individuals and 120 species were collected. No significant differences in beetle abundance or species richness were detected between substrate types. However, there were clear differences in assemblage composition between all substrate types. Our results suggest that low stumps created at final felling support as many species and individuals per volume dead wood as other dead wood substrates and that they are therefore overlooked as substrates for wood living organisms. Consequently, harvesting of low stumps might have negative effects on the diversity of saproxylic beetles, as up to 80% of the dead wood remaining on clear-cuts is in the form of low stumps. Future studies should evaluate if compensatory measures can be performed to minimize negative impacts.     

Influence of wood species on the sawdust-based cultivation ofPleurotus abalonus andPleurotus eryngii

Mycelial growth and fruit body formation ofPleurotus abalonus andP. eryngii cultured on various sawdust-based substrates from different wood species were investigated. Growth onCryptomeria japonica substrate resulted in good mycelial growth and a high yield of fruit bodies.Larix kaempferi substrate was unsuitable for the cultivation of these mushrooms. The fruit body formation rate correlated with mycelial growth from all the wood species tested. Although differences were found for mycelial growth and fruit body formation on various wood species, there were no wood species that were completely unsuitable exceptL. kaempferi. These results show that a wide range of wood species can be used for the cultivation ofP. abalonus andP. eryngii.     

6种杉阔混交林造林效果的调查研究

对6种杉阔混交林的调查研究结果表明:6种混交林均取得良好混交效果,促进了杉木树高、直径生长,提高了林分蓄积量,混交林分蓄积量比杉木纯林大4.3%~27.9%.鄂西红豆树、红锥、格氏栲在速生杉木的促进和竞争下,顶端优势明显,分叉少,干形通直,可培育大径材.观光木、乳源木莲分别与杉木混交,种间关系协调,生长稳定.杉檫混交林有利于檫树生长稳定,培育大径材,但应对檫树混交比例加以控制,不宜过大.6种阔叶树均为杉木优良的伴生树种,可大力推广.     

水性树脂底漆对木材表面润湿性的影响

水性树脂底漆对木材表面润湿性能的影响是决定木器涂装质量的关键因素。为了给木器水性漆涂装提供基本依据,选择松木、杉木、橡木、奥古曼和非洲紫檀5种木材,研究水性丙烯酸树脂底漆、水性丙烯酸改性聚氨酯底漆、双组分水性丙烯酸树脂对其表面润湿性能的影响。采用正交试验设计方案,以漆种、底漆质量分数、树种和干磨砂纸粒度为影响润湿性的因素,分别研究水性树脂底漆在木材弦、径切面的接触角大小和5种木材弦、径切面的孔槽比,分析影响木材表面润湿性的因素及原因。结果表明:4个因素水平中,底漆质量分数和漆种对木材表面润湿性的影响非常显著,树种对其影响显著,干磨砂纸粒度对其无显著影响;5种木材径切面的孔槽比高于弦切面,针叶材弦、径切面的孔槽比高于阔叶材,径切面的润湿性优于弦切面,针叶材表面润湿性优于阔叶材;此外,单组分水性树脂底漆在5种木材弦、径切面的润湿性优于双组分水性树脂底漆。因此,在木器水性漆高质量涂装中,对于不同木材种类应该选择合适的水性涂料及最优质量分数,才能保证涂装中底漆良好的质量。     

硼防腐剂与涂料复配处理木材的抗流失性能研究

文章研究了SGB硼防腐剂处理的马尾松试材经环保型水溶性涂料（WAQ）、天然植物油涂料（TRQ）及木材用户外涂料（KJQ）分别处理后的硼流失性能。结果表明硼防腐处理材经涂料再次处理后试件的抗流失性能均有改善,其中效果最好的是TRQ涂料,它与SGB共同处理的试件比单用SGB防腐剂处理的试件硼的抗流失率平均提高了36.5个百分点。     

农林废弃物基质对蓝花楹苗木生长效应的影响

以椰糠、稻壳、桉树皮为原料，按照不同体积比例配置15种混配基质，并以黄心土为对照，对16种基质进行理化性质和苗木生长状况的分析比较，通过主成分分析法筛选最佳配比。结果表明：16种基质电导率为0.19~4.63 ms·cm-1，容重为0.18~0.96 g·cm-3，总孔隙度为63.90%~93.33%，pH 值在4.19~6.27之间，不同基质配比差异均达到显著水平。混配基质 S4、S6、S14容重显著低于其他各配比基质及对照组，总孔隙度高于或显著高于其他配比基质，基质 pH 值为中性偏酸，对蓝花楹幼苗生长有较好的促进作用。对苗木各生长性状等指标进行主成分分析，结果表明：S4、S6、S14三种混配基质综合得分较高，适合作为蓝花楹幼苗培育的备选基质，但筛选出的三种混配基质有机质含量、速效氮、速效磷和速效钾含量并不突出，可能物理性质的优劣是蓝花楹幼苗在基质内生长的主要限制因素。     

The effects of several commercial wood coatings on the deterioration of biological pigments in wood exposed to UV light

This research subjected four wood species pigmented with the red stain of Scytalidium cuboideum and Acer negundo wood pigmented with the tree’s naturally occurring red stain to natural and artificial UV light. Several commercially available coatings were applied to determine the effect of coating on the degradation of both red stains over time. The red stain of Acer negundo was found to be significantly less stable in UV light than the red pigment produced by S. cuboideum on any wood species, even A. negundo. None of the tested coatings significantly increased the pigment retention time of the red stain produced by A. negundo. The red stain of S. cuboideum was significantly affected by both coating and wood species; Populus tremuloides retained pigment significantly longer than Fagus grandifolia or Acer saccharum, and the Danish oil coating retained pigment significantly longer than the lacquer, water-based polyurethane with UV inhibitors, or the uncoated samples. Overall, lacquer increased the degradation rate of the red pigment produced by S. cuboideum, with the most pronounced increase occurring on F. grandifolia. These results indicate that the red-pigmented wood produced by A. negundo may not be appropriate for applications involving UV exposure, regardless of coating utilized. However, P. tremuloides wood pigmented with S. cuboideum may be appropriate for such applications, especially if Danish oil is applied as a coating.     

不同栽培基质对3种野牡丹属植物生长的影响

为筛选野牡丹属在不同栽培基质上生长的差异，促进野牡丹属植物在城市园林中的推广应用 , 以 3 种野牡丹属植物（白花印度野牡丹 Melastoma candidum var. albiflorum、野牡丹 M. candidum 和毛稔 M. sanguineum）为试验材料，设置了 4 种不同比例泥炭土、蛭石和椰糠混合物 / 料和黄泥栽培基质处理， 比较 3 种植物的净生长量和生物量。研究结果表明，3 种野牡丹属植物苗高、冠幅、叶面积净生长量均以 黄泥栽培基质处理组较高，生长促进效应优于泥炭土、蛭石和椰糠的混合比例处理组；其地上部、地下 部生物量积累也均以黄泥栽培基质组最高。隶属函数分析结果表明，促进 3 种野牡丹植物生长效应的栽 培基质均为黄泥。     

The lamination influence on properties of agro-based particleboard

Abstract

Response surface methodology (RSM) based on a three-level, three-variable central composite rotatable design was applied to evaluate the effects of the parameters such as ratio of rice straw (Oryza sativa)/poplar (Populus deltoids) wood particle bonded with urea-formaldehyde resin in panels, species of wood veneer coating these panels and amount of adhesive in glue line on the modulus of rupture (MOR), internal bonding (IB), and thickness swelling (TS) of panels. Mathematical model equations were derived by computer simulation programming to optimize the properties of the particleboard. These equations that are second-order response functions representing MOR, IB, and TS were expressed as functions of three operating parameters of panel properties. Predicted values were found to be in a good agreement with experimental values (R ² values of 0.96, 0.98 and 0.98 for MOR, IB, and TS, respectively). This study has shown that the RSM could efficiently be applied for modeling panel properties. It was found that the variables affected the properties of panels. Straw usage up to 30% in the mixture did not cause a significant decrease in MOR, IB, and TS. Using beech veneer and 190 g/m² glue line had the highest MOR and lowest TS.     

美国人造板工业发展动向及工艺技术新进展

本文详细论述了美国人造板工业的基本情况、主要产品的开发和研究动向、新工艺和新技术的进展、新型人造板的发展趋势、新胶种的研究和开发、施胶技术的新进展、人工林木材在人造板工业中的开发与利用、人造板的产量和进出口贸易、供需矛盾及解决途径、实现发展目标所采取的措施等。     

Evaluation of the photo stabilising efficiency of clear coatings comprising organic UV absorbers and mineral UV screeners on wood surfaces

A study of the surface discolouration of clear coated wood during artificial and outdoor weathering and its prevention using clear coatings comprising organic UV absorbers (UVA) and mineral UV screeners was carried out. It was shown that the use of UVA and UV screeners in clear coatings was very effective in reducing photodegradation of the wood surface. Preliminary irradiation trials with Xenon arc light showed that the UV screener TiO₂ led to the least discolouration of the coated wood surface, closely followed by UVA of the hydroxyphenyl-s-triazine class (HPT). The artificial and outdoor weathering trials indicated that UVA of the HPT class stabilised the colour of the wood surface better than UVA of the 2-(2-hydroxyphenyl)-benzotriazole class (BTZ). Comparison of different artificial weathering methods indicated that Xenon arc light weathering showed the best match to the proceeding discolouration of the clear coated wood panels during outdoor weathering.     

Image analysis study of mould susceptibility of spruce and larch wood dried or heat-treated at different temperatures

Abstract

In this study, mould growth on wood was investigated by image analysis. The studied parameters were drying and heat-treatment temperatures (20–210°C), original and resawn surface and different wood species (spruce and larch). Small specimens—some of which were inoculated with a spore suspension—were stored under humid conditions and photographed once a week. Mould growth was assessed by image analysis. In general, results found in earlier studies regarding the influence of several parameters could be confirmed. Image analysis was found to be a useful method to quantify mould growth in an objective and reproducible way.